What is atrial fibrillation

Understanding Atrial Fibrillation

Atrial fibrillation (AFib or AF) is a condition where the heart's upper chambers, called atria, beat irregularly and out of synchronization with the lower chambers (ventricles). Instead of contracting in an organized, coordinated manner to pump blood efficiently, the atria quiver chaotically. This irregular rhythm disrupts the normal flow of blood through the heart and into the rest of the body.

How AFib Develops

The heart maintains its rhythm through a natural electrical system. Normally, electrical signals originate from the sinoatrial (SA) node and travel in an organized pattern, causing coordinated contractions. In atrial fibrillation, abnormal electrical signals fire rapidly and chaotically throughout the atria, sometimes 100-350 times per minute, far exceeding the normal heart rate of 60-100 beats per minute.

These chaotic signals cause the atria to quiver rather than contract effectively. Consequently, blood pools in the atria instead of flowing smoothly into the ventricles and out to the body.

Types of Atrial Fibrillation

AFib is classified into several types:

• Paroxysmal AFib: Episodes come and go, lasting minutes to hours, then stopping on their own
• Persistent AFib: The irregular rhythm lasts longer than a week or requires treatment to restore normal rhythm
• Long-standing Persistent AFib: AFib has been present for more than one year
• Permanent AFib: The rhythm cannot be restored, and treatment focuses on rate control and stroke prevention

Risk Factors and Causes

Common risk factors include advanced age, high blood pressure, heart disease, diabetes, obesity, chronic kidney disease, sleep apnea, and excessive alcohol consumption. Some people develop AFib without identifiable risk factors, referred to as lone atrial fibrillation.

Complications of AFib

The most serious complication is stroke. Sluggish blood flow in the fibrillating atria allows blood clots to form. If a clot dislodges, it can travel to the brain, causing a stroke. AFib increases stroke risk by 4-5 times compared to people without the condition. Other complications include heart failure (due to inefficient pumping), rapid ventricular response (dangerously fast heart rate), and reduced quality of life.

Symptoms and Diagnosis

Symptoms vary widely. Some people experience palpitations (awareness of rapid or irregular heartbeats), shortness of breath, chest discomfort, fatigue, or lightheadedness. Others have no symptoms and discover AFib incidentally during medical evaluation. Diagnosis typically involves an electrocardiogram (ECG), which can capture the characteristic irregular rhythm. Doctors may also use Holter monitors (24-hour ECG) or event recorders to detect paroxysmal episodes.

Treatment Approaches

Treatment goals focus on reducing stroke risk, controlling heart rate, and restoring normal rhythm when possible. Options include:

• Medications: Beta-blockers or calcium channel blockers control heart rate; antiarrhythmic drugs restore rhythm; anticoagulants prevent blood clots
• Cardioversion: Electrical shock or medications to restore normal rhythm
• Catheter ablation: Minimally invasive procedure to locate and destroy tissue causing abnormal electrical signals
• Lifestyle changes: Reducing alcohol, managing blood pressure and weight, treating sleep apnea